Update to add get() and setdefault() as supported mapping operations, and
add a list of the mapping methods which are not supported (per Barry's
comments).
diff --git a/Doc/lib/librfc822.tex b/Doc/lib/librfc822.tex
index 56f6c74..55ec5c2 100644
--- a/Doc/lib/librfc822.tex
+++ b/Doc/lib/librfc822.tex
@@ -215,11 +215,17 @@
In particular: \code{\var{m}[name]} is like
\code{\var{m}.getheader(name)} but raises \exception{KeyError} if
there is no matching header; and \code{len(\var{m})},
+\code{\var{m}.get(name\optional{, deafult})},
\code{\var{m}.has_key(name)}, \code{\var{m}.keys()},
-\code{\var{m}.values()} and \code{\var{m}.items()} act as expected
+\code{\var{m}.values()} \code{\var{m}.items()}, and
+\code{\var{m}.setdefault(name\optional{, default})} act as expected
(and consistently). \class{Message} instances also support the
mapping writable interface \code{\var{m}[name] = value} and \code{del
-\var{m}[name]}.
+\var{m}[name]}. \class{Message} objects do not support the
+\method{clear()}, \method{copy()}, \method{popitem()}, or
+\method{update()} methods of the mapping interface. (Support for
+\method{.get()} and \method{.setdefault()} was only added in Python
+2.2.)
Finally, \class{Message} instances have two public instance variables: